The present invention relates to a method of correcting coin data and an apparatus for inspecting coins, wherein data for discriminating authenticity and denominations of coins inserted in an automatic vending machine, a public telephone booth, and the like is corrected.
An inspection apparatus of this type is disclosed in U.S. Pat. No. 3,918,565. In this apparatus, physical characteristics, such as the thickness diameter and the like, of a coin are detected by detectors as electrical signals. Upper and lower limit values corresponding to detection outputs of the respective physical characteristics are stored in a memory. The upper and lower limit values are compared with the outputs from the detectors to determine authenticity and denomination of coins.
All data corresponding to all denominations (types) of coins and their physical characteristics and the corresponding upper and lower limit values must be read out from a memory, and detection outputs corresponding to the numbers of denominations and physical characteristics must be compared with the upper and lower limit values. For this reason, high-speed determination operations cannot be performed, and power consumption is increased. In addition, if these operations are performed by a processor, a program is complicated and a time margin for other control operations is decreased. Since high-speed determination operations cannot be performed, a determination time is prolonged. Therefore, a coin insertion time interval is limited, and design of coin paths is also limited.
In order to solve the above problems, an arrangement disclosed in U.S. Pat. No. 4,660,705 is proposed. In this arrangement, physical characteristic determination signals for coins are stored at bit positions corresponding to the denominations at addresses of a memory. The physical characteristics of coins are detected by detectors as electrical signals. These detection outputs are converted into digital signals by an A/D converter, and the digital signals are used as memory address signals, thereby using the contents of the memory as authenticity determination signals.
The conventional methods described above, however, must correct sensor outputs upon changes in environmental changes, and deterioration over time must also be corrected to result in a complex correction circuit. In addition, initialization must be performed at each installation site, resulting in poor operability.